It is the object of this invention to propose a simple feeder drive mechanism which allows to obviate the drawbacks of the preceding state of the art, a mechanism which makes it unnecessary to stop the rotating drum during the single-sheet gripping phase, ensuring thus that at the moment of gripping the single sheet, the drum together with the grippers rotates at a minimum speed which, after the sure gripping of the sheet, is again accelerated to the maximum speed until the next sheet gripping phase is reached.
The said object is reached according to this invention by driving the gripper-carrying drum with a mechanism having a rotating guide component provided with a longitudinal groove with a roller, slidingly seated in this groove, near the circumference of a revolving disk and connected to a shaft controlling the motion of the drum and with the center of rotation of the said disk being displaced with respect to the centre of rotation of the driving shaft of the grooved component.
With a similar mechanism for controlling the action of the respective gripper drums of an automatic feeder, the speed of the revolving drum is brought by simple and secure means from a minimum (during the sheet gripping phase) to a maximum, followed by a new slowing-down phase, without any abrupt stoppage.
The mechanism according to this invention will now be described in detail with reference to a preferred embodiment thereof given by way of example without being limited thereto, and on hand of the accompanying drawings, in which: